Neurodevelopmental, cognitive, behavioural and mental health impairments following childhood malnutrition: a systematic review

Background Severe childhood malnutrition impairs growth and development short-term, but current understanding of long-term outcomes is limited. We aimed to identify studies assessing neurodevelopmental, cognitive, behavioural and mental health outcomes following childhood malnutrition. Methods We systematically searched MEDLINE, EMBASE, Global Health and PsycINFO for studies assessing these outcomes in those exposed to childhood malnutrition in low-income and middle-income settings. We included studies assessing undernutrition measured by low mid-upper arm circumference, weight-for-height, weight-for-age or nutritional oedema. We used guidelines for synthesis of results without meta-analysis to analyse three outcome areas: neurodevelopment, cognition/academic achievement, behaviour/mental health. Results We identified 30 studies, including some long-term cohorts reporting outcomes through to adulthood. There is strong evidence that malnutrition in childhood negatively impacts neurodevelopment based on high-quality studies using validated neurodevelopmental assessment tools. There is also strong evidence that malnutrition impairs academic achievement with agreement across seven studies investigating this outcome. Eight of 11 studies showed an association between childhood malnutrition and impaired cognition. This moderate evidence is limited by some studies failing to measure important confounders such as socioeconomic status. Five of 7 studies found a difference in behavioural assessment scores in those exposed to childhood malnutrition compared with controls but this moderate evidence is similarly limited by unmeasured confounders. Mental health impacts were difficult to ascertain due to few studies with mixed results. Conclusions Childhood malnutrition is associated with impaired neurodevelopment, academic achievement, cognition and behavioural problems but evidence regarding possible mental health impacts is inconclusive. Future research should explore the interplay of childhood and later-life adversities on these outcomes. While evidence on improving nutritional and clinical therapies to reduce long-term risks is also needed, preventing and eliminating child malnutrition is likely to be the best way of preventing long-term neurocognitive harms. PROSPERO registration number CRD42021260498.


Adjusted analysis:
Weight at 2 years associated with BSID outcome, but early and late growth faltering before 1 year not independently associated with BSID scores after adjusting for weight at 2 years and other covariates (sex, mother's education, possessions).

Overall Findings:
Significantly lower psychomotor and mental scores at 2 years in early growth falterers and late growth Overall findings: Malnutrition survivors were significantly more likely to be in a lower grade at school than controls adjusted for confounding variables. Malnutrition survivors had poorer cognition scores than controls, but differences were not statistically significant when adjusted for confounding variables.

Adjusted analysis:
When results adjusted via stepwise regression, visual processing and short-term memory remained significantly correlated when adjusted for maternal education, family size, and household roof type.
Overall findings: Scores on short-term memory and visual processing were significantly poorer in cases compared to controls when adjusted for confounding variables.   Adjusted analysis: Early malnutrition predicted cognitive function and exam score in childhood after adjusting for childhood standard of living.
Overall findings: Malnutrition predicted common entrance exam score and cognitive functioning after adjusting for childhood standard of living.  Wasting was not statistically associated with any developmental outcome variables after adjusting for vector of child, parent, caregiver and household-level characteristics.

Overall findings:
Wasting was not associated with a difference in behaviour after adjusting for confounding variables. Overall findings: Cases had significantly less disability in terms of social relationships than the community controls but had statistically significant lower self-esteem than the controls unadjusted for confounding variables. Externalizing behaviour problems at age 8: Malnourished children had higher overall externalizing behaviour scores (both hyperactivity and aggression) than controls.

Adjusted analysis:
Main effect of malnutrition remained significant after controlling for psychosocial adversity but was abolished after controlling for cognitive ability.
Externalizing behaviour problems at age 11: Malnourished children had higher externalising behaviour scores (hyperactivity only) at age 11 than nonmalnourished children.

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Adjusted analysis: Main effect of malnutrition remained significant after controlling for psychosocial adversity but was abolished after controlling for cognitive ability.
Externalizing behaviour problems at age 17: Malnourished group had significantly higher scores on conduct disorder and motor excess but not attention problems or socialized aggression.

Adjusted analysis:
Main effect of malnutrition remained significant after adjusting for psychosocial adversity and cognitive ability.
Sample size: Malnutrition group n=235, Control group n=807 Overall Findings: Children with malnutrition were more aggressive or hyperactive at age 8 years, had more externalizing problems at age 11, and had greater conduct disorder and excessive motor activity at age 17 after adjusting for confounding variables. Overall findings: Adults with history of infant malnutrition showed an increase in most SCID-II and NEO FFM PD personality scores compared to those with little or no exposure to either adversity. Few personality disorder score differences were statistically significant however and results differed depending on the assessment tool used. Overall findings: CAARS scores were higher (indicating more attention problems) in the previously malnourished group. There were significant differences in inattention and DSM-IV ADHD symptom scores after adjusting for confounding variables. Differences in CPT scores were attenuated after adjusting for confounding variables. Teacher-behaviour-questionnaire:

Barbados Nutrition Study
All four items showed a higher level prevalence of aberrant behavior in the previously malnourished children as compared with the comparison group.

Adjusted analysis:
The difference was no-longer-significant with IQ and childhood standard of living included in the model Overall findings: Self-reported conduct problems were more prevalent among previously malnourished youth. The associated was no longer significant when adjusted for confounding variables. Overall findings: Depressive symptoms and inattention were higher in those with malnutrition but there were no significant differences when adjusting for confounding variables.